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Fall Creek Drawdown - Taylor

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Benefits and Impacts to Fish, Flows, and the Downstream Environment. Presented by Greg Taylor, US Army Corps of Engineers.

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Fall Creek Drawdown - Taylor

  1. 1. Fall Creek Drawdown: Benefits and Impacts to Fish, Flows, and the Downstream Environment Greg Taylor Fisheries Biologist Willamette / Rogue Projects Within Our Reach December 11th, 2012US Army Corps of EngineersBUILDING STRONG®
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  4. 4. Operations Minimum conservation pool (728) Dec-Jan Refill Feb. – mid May Drawdown Sept-Nov.
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  6. 6. Fall Creek Drawdown Biological Objectives Increased fish passage efficiency Increased fish passage survival Reduced predation and competition for rearing juvenile chinook salmon BUILDING STRONG®
  7. 7. 2011/12 Drawdown830810790770750730  Minimum conservation pool710690670 BUILDING STRONG®
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  9. 9. UpperReservoir Upper Reservoir BUILDING STRONG®
  10. 10. Sediment in Reservoir BUILDING STRONG®
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  12. 12. RO Intake and Fish Horns BUILDING STRONG®
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  16. 16. Gravel accumulation below dam BUILDING STRONG®
  17. 17. Lower Fall Creek BUILDING STRONG®
  18. 18. Confluence of Fall Creek andMiddle Fork Willamette River BUILDING STRONG®
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  20. 20. Chinook Migration Timing vs Elevation 830 180 810 160 790Reservoir Elevation (feet) 140 Chinook Count 770 120 750 100 Min. Con. Pool (728’) 80 730 60 710 40 690 20 670 0 Trap Off BUILDING STRONG®
  21. 21. Summary Reservoir drawdown increased fish passage efficiency, survival, and reduce predation and competition for juvenile chinook salmon rearing in the reservoir Physically reconnect the river above and below the dams Large Quantity of sediment released downstream during drawdown ► Sediment is silt, sand, and gravel ► Helps replenish sediment downstream of dams which may contribute to ecosystem health (salmon spawning in newly deposited gravel). Obstacles to implementing further drawdowns: ► 1) Impacts to downstream users and the environment • Environmental compliance ► 2) Impacts to other USACE authorized purposes BUILDING STRONG®

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